It was 45 F at half time when they were checked.
They would need to have filled and checked their balls at 50 F hotter. So a 95 F room.
“They would need to have filled and checked their balls at 50 F hotter. So a 95 F room.”
Remember that a digital readout is always + or - one digit, that’s just the way it is...
Also, it depends on the mixture of gases in the ball. Add a smigion of low vapor pressure gas (H2O for example) and you could get the pressure drop at 45 degrees.
When a gas is pressurized, its temperature rises. If these balls were filled quickly, the inside temperature would have been higher than the room temperature — possibly above 95*F. After a few minutes, the inside of the ball would have reached room temperature, and thus have a lower pressure. However, unless the league rules mention all those variables; the balls might actually have been in compliance, when they were filled.
It shouldn’t be difficult to conduct an experiment, supervised by league officials. Fill a ball indoors — to the minimum allowable pressure. Take outdoors and wait for a half hour or so, and check the pressure.
There's a little more going on than that. Suppose the pressure gauges are digital and read to the nearest 0.5 psi (plausible since all reported pressures I've heard were in increments of 0.5). Then you just have to go over 12.25 to read 12.5. Add in that the air warms up when compressed, so a freshly inflated ball in a 75 degree room should read a higher pressure initially than it would an hour later in the same room. The end result from intentionally staying just on the side of arguably following the rules would be 11 psi balls by halftime at 45 degrees F.
Or the addition of dry to wet leather.
From 75F to 50F all by itself is a drop of 1.2 PSI.